This invention relates to the field of video display, and in particular to the generation and timing of deflection waveform correction signals for cathode ray tube display.
In a projection type video display, the usual geometrical raster distortions associated with a cathode ray tube display may be exacerbated by the use of CRTs with curved, concave spherical phosphor display surfaces and the inherent magnification in the optical projection path. A curved face plate CRT may offer benefits in terms of a reduction of projection path length, and optical imaging simplification. However since the displayed image is composed of the three projected rasters in register on the screen, multiple corrective deflection waveforms are required to compensate for geometrical distortions resulting from the combination of electron beam deflection, tube face plate shape and optical display path. Hence, to satisfy more stringent convergence requirements imposed by large screen viewing the correction waveforms must be specially shaped, stably generated and accurately timed.